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Journal articles on the topic 'Variable frequency microwave'

To see the other types of publications on this topic, follow the link: Variable frequency microwave.

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Tanikella, Ravindra V., Sue A. Bidstrup Allen, and Paul A. Kohl. "Variable-frequency microwave curing of benzocyclobutene." Journal of Applied Polymer Science 83, no. 14 (February 14, 2002): 3055–67. http://dx.doi.org/10.1002/app.10286.

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2

Bows, J. R. "Variable Frequency Microwave Heating of Food." Journal of Microwave Power and Electromagnetic Energy 34, no. 4 (January 1999): 227–38. http://dx.doi.org/10.1080/08327823.1999.11688410.

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3

Ku, H. S., M. MacRobert, E. Siores, and J. A. R. Ball. "Variable frequency microwave processing of thermoplastic composites." Plastics, Rubber and Composites 29, no. 6 (June 2000): 278–84. http://dx.doi.org/10.1179/146580100101541076.

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4

Famsworth, K. D., R. N. Manepalli, S. A. Bidstrup-Allen, and P. A. Kohl. "Variable frequency microwave curing of photosensitive polyimides." IEEE Transactions on Components and Packaging Technologies 24, no. 3 (2001): 474–81. http://dx.doi.org/10.1109/6144.946496.

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5

Jiang, Hongjin, Kyoung-sik Moon, Zhuqing Zhang, Suresh Pothukuchi, and C. P. Wong. "Variable Frequency Microwave Synthesis of Silver Nanoparticles." Journal of Nanoparticle Research 8, no. 1 (February 2006): 117–24. http://dx.doi.org/10.1007/s11051-005-7522-6.

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6

Antonio, Christian, and Piyachat Watanachai. "Variable Frequency Microwave Curing of SU8 Photoresist Films." Advanced Materials Research 931-932 (May 2014): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.101.

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Photoresist used in the fabrication of Microelectrochemical Systems (MEMS) has traditionally been processed using conventional curing technology. This type of curing is often time intensive and results in non-uniform products. A uniform bake of the layer is not always possible due to the mechanisms of heat transfer conventional curing offers, leading to poor pattern resolution, formation of micro-cracks and severe outgassing occurring as a consequence. The Variable Frequency Microwave (VFM) Technique was successfully utilised in this study as an alternative method for the processing of negative tone SU8 photoresist. The VFM method was compared to the conventional processing method, which utilises a Hotplate, and a hybrid method utilizing both Hotplate and the VFM and found that an increase on the degree of cure was observed using the VFM at similar processing temperatures which means that SU8 curing at lower temperatures or rapid curing is possible. The increase in cure rates can be attributed to a combination of heat transfer and the unique capability of microwave to couple with the sample. Optical studies of the microstructures fabricated suggest that films that have a degree of cure of <60% resulted in poor quality microstructures. The VFM was found to achieve satisfactory microstructures at most of the temperatures tested as compared to the other two methods tested.

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7

Ku, H. S., E. Siores, and J. A. R. Ball. "Application of Variable Frequency Microwave (VFM) to Adhesives." Journal of Electromagnetic Waves and Applications 19, no. 11 (January 2005): 1467–84. http://dx.doi.org/10.1163/156939305775701903.

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8

Raeis-Zadeh, Mehrsa, Christina Bins, Emily Korby, Sang Lee, and Paul A. Kohl. "Variable-Frequency Microwave Curing of Photosensitive Polynorbornene Dielectric." ECS Journal of Solid State Science and Technology 1, no. 1 (2012): N6—N13. http://dx.doi.org/10.1149/2.029201jss.

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9

Horikoshi, Satoshi, Yuuhei Arai, Iftikhar Ahmad, Clayton DeCamillis, Keith Hicks, Bob Schauer, and Nick Serpone. "Application of Variable Frequency Microwaves in Microwave-Assisted Chemistry: Relevance and Suppression of Arc Discharges on Conductive Catalysts." Catalysts 10, no. 7 (July 11, 2020): 777. http://dx.doi.org/10.3390/catal10070777.

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The application and advantages of variable frequency microwaves (VFM; range, 5.85–6.65 GHz) are reported for the first time in microwave chemistry, particularly when carrying out reactions catalyzed by metallic conductive catalysts so as to avoid the formation of arc discharges, and especially when using a strong microwave absorber such as activated carbon (AC) particulates as supports of metal-based catalysts. Two model reactions performed in low boiling point nonpolar solvents are described wherein arc discharges easily occur under the more conventional fixed frequency microwave (FFM) approach: (i) the synthesis of 4-methylbiphenyl (4MBP) by the Suzuki-Miyaura cross-coupling process catalyzed by Pd particles supported on AC particulates (Pd/AC), and (ii) the synthesis of toluene via the dehydrogenation of methylcyclohexane (MCH) catalyzed by Pt particles dispersed on AC particulates (Pt/AC). Contrary to the usage of fixed frequency microwaves (5.85 GHz and 6.65 GHz), the use of VFM microwaves increased the chemical yields of 4MBP {49% versus 5–8% after 60 min} and toluene {89% versus 24% after 10 min} by suppressing the formation of discharges that otherwise occur on the catalyst/AC surface with FFM microwaves. Consequently, relative to the latter approach, the VFM technology is significantly advantageous, especially in reactions with solid conductive catalysts, not least of which are the reduction in power consumption, thus energy savings, and the prevention of potential mishaps.

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10

Ku, H. S., M. MacRobert, E. Siores, and J. A. R. Ball. "Characterisation of thermoplastic matrix composites using variable frequency microwave." Plastics, Rubber and Composites 29, no. 6 (June 2000): 285–87. http://dx.doi.org/10.1179/146580100101541085.

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11

Tanaka, Kenji, Sue Ann Bidstrup Allen, and Paul A. Kohl. "Variable Frequency Microwave Curing of Amide-Epoxy Based Polymers." IEEE Transactions on Components and Packaging Technologies 30, no. 3 (September 2007): 472–77. http://dx.doi.org/10.1109/tcapt.2007.900061.

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12

Moon, Kyoung-Sik, Yi Li, Jianwen Xu, and C. P. Wong. "Lead-free interconnect technique by using variable frequency microwave." Journal of Electronic Materials 34, no. 7 (July 2005): 1081–88. http://dx.doi.org/10.1007/s11664-005-0099-0.

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13

Matsutani, Hiroshi, Takashi Hattori, Masayuki Ohe, Takumi Ueno, Robert L. Hubbard, and Zak Fathi. "Low Temperature Curing of Polyimide Precursors by Variable Frequency Microwave." Journal of Photopolymer Science and Technology 18, no. 2 (2005): 327–32. http://dx.doi.org/10.2494/photopolymer.18.327.

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14

Ku, Harry Siu-Lung, and Talal Yusaf. "PROCESSING OF COMPOSITES USING VARIABLE AND FIXED FREQUENCY MICROWAVE FACILITIES." Progress In Electromagnetics Research B 5 (2008): 185–205. http://dx.doi.org/10.2528/pierb08011304.

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15

Mattar, K. E., and M. E. Brodwin. "A variable frequency method for wide-band microwave material characterization." IEEE Transactions on Instrumentation and Measurement 39, no. 4 (1990): 609–14. http://dx.doi.org/10.1109/19.57242.

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16

Klinger, Ofir, Yonatan Stern, Thomas Schneider, Kambiz Jamshidi, and Avi Zadok. "Long Microwave-Photonic Variable Delay of Linear Frequency Modulated Waveforms." IEEE Photonics Technology Letters 24, no. 3 (February 2012): 200–202. http://dx.doi.org/10.1109/lpt.2011.2176483.

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17

Davis, Cleon E., Anthony J. Dickherber, William D. Hunt, and Gary S. May. "In Situ Acoustic Temperature Measurement During Variable-Frequency Microwave Curing." IEEE Transactions on Electronics Packaging Manufacturing 31, no. 4 (October 2008): 273–84. http://dx.doi.org/10.1109/tepm.2008.2004570.

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18

Mead, Patricia F., Aravind Ramamoorthy, and Shapna Pal. "Investigation of Variable Frequency Microwave Processing for Electronic Packaging Applications." Journal of Electronic Packaging 125, no. 2 (June 1, 2003): 294–301. http://dx.doi.org/10.1115/1.1571076.

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This paper summarizes the effects of the variable frequency microwave (VFM) technique for rapid cure of polymeric encapsulants (such as flip-chip underfills) on the performance and reliability of electronic devices. Initial electrical performance of selected commercial IC packages following the application of VFM radiation stress has been recorded, and the performance has been compared to packages that were treated with comparable temperature cycles as applied in a convection oven. Failure analysis was performed on packages that showed electrical degradation to identify likely degradation and failure modes of the packaged ICs. Overall, our results show that VFM technology can safely be applied as an electronic packaging technology. However, proper control of VFM operating parameters is needed to ensure favorable performance of electronic devices.

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19

Tan, X., N. Munroe, Z. Fathi, and R. Garard. "Firing of Bauxite Extrudates in a Variable Frequency Microwave Furnace." Journal of Microwave Power and Electromagnetic Energy 33, no. 1 (January 1998): 31–35. http://dx.doi.org/10.1080/08327823.1998.11688357.

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20

Kuki, T., H. Fujikake, and T. Nomoto. "Microwave variable delay line using dual-frequency switching-mode liquid crystal." IEEE Transactions on Microwave Theory and Techniques 50, no. 11 (November 2002): 2604–9. http://dx.doi.org/10.1109/tmtt.2002.804510.

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21

Mead, Patricia F., Aravind Ramamoorthy, Shapna Pal, Z. Fathi, and I. Ahmad. "Variable Frequency Microwave Processing of Underfill Encapsulants for Flip-Chip Applications." Journal of Electronic Packaging 125, no. 2 (June 1, 2003): 302–7. http://dx.doi.org/10.1115/1.1571077.

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This paper discusses an innovative technique for rapid cure of polymeric encapsulants such as underfills used in direct chip attach devices using variable frequency microwaves (VFM). VFM processing reduces the cure time for underfill encapsulants to 10 min or less, as compared to 30 or more minutes when using convection oven methods. We report here the results of our investigations measuring key material attributes of VFM and conventionally cured underfill encapsulant samples, and we also have characterized voiding and delamination characteristics of flip-chip with underfill test structures. Finally, particle settling in the flip-chip with underfill test structures has been characterized. Our results show that the VFM technique produces underfill attributes that are comparable to conventionally cured samples.

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22

Antonio, C., R. Deam, and A. Taube. "A Review of the Variable Frequency Microwave Technology in Material Processing." Journal of Microwave Power and Electromagnetic Energy 38, no. 1 (January 2003): 75–87. http://dx.doi.org/10.1080/08327823.2003.11688488.

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23

Klinger, Ofir, Yonatan Stern, Fabian Pederiva, Kambiz Jamshidi, Thomas Schneider, and Avi Zadok. "Continuously variable long microwave-photonic delay of arbitrary frequency-chirped signals." Optics Letters 37, no. 19 (September 18, 2012): 3939. http://dx.doi.org/10.1364/ol.37.003939.

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24

Diop, Mamadou Diobet, Marie-Claude Paquet, Dominique Drouin, and David Danovitch. "Interactions between Variable Frequency Microwave Underfill Processing and High Performance Packaging Materials." International Symposium on Microelectronics 2013, no. 1 (January 1, 2013): 000461–66. http://dx.doi.org/10.4071/isom-2013-wa21.

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Variable frequency microwave (VFM) has been recently proposed as an alternative underfill curing method that provides flip chip package warpage improvement as well as potential underfill cure time reductions. The current paper outlines how such advantages in VFM processing of underfill can be compromised when applied to high performance organic packages. VFM recipes for three underfill materials were developed by performing several VFM curing runs followed by curing rate measurements using the differential scanning calorimetry method. The VFM curing rate was seen to strongly dependent upon the underfill chemistry. By testing flip chip parts that comprised large and high-end substrates, we showed that the underfill material has negligible impact on VFM warpage with the major cause attributed to the coefficient of thermal expansion mismatch between the die and the substrate. Comparison between the convection and the VFM methods indicated two warpage tendencies that depended upon the VFM curing temperature. First, when both curing methods used comparably high temperatures, warpage increases up to about + 20% were found with VFM. This unexpected result was explained by the high-density Cu loading of the substrate which systematically carried heat generated by VFM energy from the die/underfill system to the substrate. Since this high-end substrate consists of sequential dielectric/Cu layers with asymmetric distribution of Cu, additional stresses due to local CTE mismatches between the Cu and the dielectric layers were induced within the substrate processed with VFM. Second, warpage reductions down to about − 22% were obtained at the VFM curing temperature of 110°C with a curing time similar to that of convection cure. This suggests that the negative effect of the local CTE mismatches were no longer at play at the lower VFM temperatures and that the significantly lower final cure temperatures produced lower total shrinkage of the die and the substrate. Finally, due to lower elastic moduli, the cured VFM parts showed better mechanical reliability with no fails up to 1500 cycles.

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25

Li, Xiang, De-Wei Wu, Qiang Miao, and Chao Chen. "Discussion on the frequency and bandwidth of continuous variable entangled microwave signal." Results in Physics 14 (September 2019): 102447. http://dx.doi.org/10.1016/j.rinp.2019.102447.

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26

Davis, C. E., and G. S. May. "Neural Network Control of Variable-Frequency Microwave Processing of Polymer Dielectric Curing." IEEE Transactions on Electronics Packaging Manufacturing 31, no. 2 (April 2008): 104–13. http://dx.doi.org/10.1109/tepm.2008.919345.

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27

Rao, Mulpuri V., Y. L. Tian, Syed B. Qadri, Jaime A. Freitas, and Roberta Nipoti. "Ultra Fast High Temperature Microwave Annealing of Ion Implanted Large Bandgap Semiconductors." Materials Science Forum 645-648 (April 2010): 709–12. http://dx.doi.org/10.4028/www.scientific.net/msf.645-648.709.

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In this work, the surface, lattice and electrical properties of implanted 4H-SiC, GaN and ZnO, annealed by a novel ultra-fast microwave heating method, are compared to that of conventional annealing methods. In this new method, amplified and variable frequency microwaves from a signal generator are directly coupled to the semiconductor sample through a microwave head. Since, the microwaves are only absorbed by the sample, without heating of the ambient, ultra-high heating (> 2000°C/s) and cooling rates and very high (2100°C) annealing temperatures can be reached. For Al and P species implants into 4H-SiC, record low resistivity values were achieved with a lattice quality better than that of the virgin crystal. This annealing method improved the lattice quality of un-implanted region below the surface implanted region as well. Improved material characteristics were also obtained for GaN and ZnO.

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28

Ku, H. S., F. Siu, E. Siores, and J. A. R. Ball. "Variable frequency microwave (VFM) processing facilities and application in processing thermoplastic matrix composites." Journal of Materials Processing Technology 139, no. 1-3 (August 2003): 291–95. http://dx.doi.org/10.1016/s0924-0136(03)00238-3.

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29

Venere, Alejandro J., Martin Hurtado, Ramon Lopez La Valle, and Carlos H. Muravchik. "New Design of a Variable Impedance Based on Polarized Diodes at Microwave Frequency." IEEE Microwave and Wireless Components Letters 27, no. 5 (May 2017): 470–72. http://dx.doi.org/10.1109/lmwc.2017.2690877.

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30

Ku, H. S., E. Siores, J. A. R. Ball, A. Taube, and F. Siu. "Lap shear strength comparison between different random glass fibre reinforced thermoplastic matrix composites bonded by adhesives using variable-frequency microwave irradiation." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 217, no. 1 (January 1, 2003): 65–75. http://dx.doi.org/10.1177/146442070321700108.

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This paper compares the lap shear strengths of three types of random glass fibre reinforced thermoplastic matrix composite joined by adhesives using microwave energy. Variable-frequency microwave (VFM) (2-18 GHz) facilities are used to join 33 wt % random glass fibre reinforced low-density polyethylene composite [LDPE/GF (33%)], 33 wt % random glass fibre reinforced polystyrene composite [PS/GF (33%)] and 33 wt % random glass fibre reinforced nylon 66 composite [nylon 66/GF (33%)]. With a given power level, the composites were exposed for various times to microwave irradiation. The primer or coupling agent used was a 5 min two-part adhesive.

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31

Gedye, R. N., and J. B. Wei. "Article." Canadian Journal of Chemistry 76, no. 5 (May 1, 1998): 525–32. http://dx.doi.org/10.1139/v98-075.

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Several different reactions have been studied to determine whether they occur more rapidly than conventionally heated reactions at atmospheric pressure. Small rate enhancements have been observed for some reactions carried out under microwave reflux in a modified domestic microwave oven. The Knoevenagel reaction of acetophenone with ethyl cyanoacetate was shown to have a rate enhancement of 2.5 times. However this reaction showed no rate increase over conventional heating, at the same temperature, in a variable-frequency microwave oven. It is therefore probable that the small rate enhancements observed in these experiments, using microwave heating, were due to hot spots or superheating of the solvent rather than to nonthermal effects.Key words: microwave, nonthermal effects, superheating, hot spots.

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32

Ku, H. S., F. Siu, E. Siores, J. A. R. Ball, and A. S. Blicblau. "Applications of fixed and variable frequency microwave (VFM) facilities in polymeric materials processing and joining." Journal of Materials Processing Technology 113, no. 1-3 (June 2001): 184–88. http://dx.doi.org/10.1016/s0924-0136(01)00642-2.

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33

Zymelka, Daniel, Boris Matveev, Sergey Aleksandrov, Galina Sotnikova, Gennady Gavrilov, and Mohamed Saadaoui. "Time-resolved study of variable frequency microwave processing of silver nanoparticles printed onto plastic substrates." Flexible and Printed Electronics 2, no. 4 (October 27, 2017): 045006. http://dx.doi.org/10.1088/2058-8585/aa900a.

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34

Yota, Jiro, Hoa Ly, Ravi Ramanathan, Hsiang-Chih Sun, Dragana Barone, Thinh Nguyen, Kohji Katoh, Masayuki Ohe, Robert L. Hubbard, and Keith Hicks. "Variable Frequency Microwave and Convection Furnace Curing of Polybenzoxazole Buffer Layer for GaAs HBT Technology." IEEE Transactions on Semiconductor Manufacturing 20, no. 3 (August 2007): 323–32. http://dx.doi.org/10.1109/tsm.2007.901410.

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35

Tanikella, R. V., Taehyun Sung, S. A. Bidstrup-Allen, and P. A. Kohl. "Rapid curing of positive tone photosensitive polybenzoxazole based dielectric resin by variable frequency microwave processing." IEEE Transactions on Components and Packaging Technologies 29, no. 2 (June 2006): 411–19. http://dx.doi.org/10.1109/tcapt.2006.875882.

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36

Sung, Taehyun, Sue A. Bidstrup Allen, and Paul A. Kohl. "Low Temperature Rapid Curing of Polymer Dielectrics on Metallized Organic Laminates by Variable Frequency Microwave Processing." Journal of Microelectronics and Electronic Packaging 2, no. 2 (April 1, 2005): 142–54. http://dx.doi.org/10.4071/1551-4897-2.2.142.

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The curing of polymer dielectrics on organic laminates by variable frequency microwave (VFM) processing was studied. Polymer dielectrics, such as polyimides, normally require long cure times at elevated temperatures resulting in processing incompatibility with epoxy-based laminates due to the low thermal stability of the organic laminates. In this study, VFM processing was investigated as an alternative, low temperature technique for curing polyimide and benzycyclobutene (BCB) on metallized bismaleimide triazine/epoxy (BT) board. The VFM heating characteristics of the metallized (BT) boards were studied. The VFM heating rates of the BT boards strongly depended on the configuration, size, and shape of the copper patterns on the boards. The VFM curing of polyimide and BCB on the metallized BT boards was also performed. The curing condition was optimized to minimize board degradation. At the same board degradation level, the chemical, thermo-mechanical and electrical properties of the VFM cured film were compared with a film thermally cured using a conventional convection furnace. A higher degree of curing and lower dielectric constant was achieved for benzocyclobutene (BCB) films on BT boards processed using VFM curing than was obtained using conventional curing. VFM cured polyimide (PI 2611) showed a similar degree of curing and Young's modulus to conventionally cured PI 2611. However, the VFM cured PI 2611 showed a higher residual content solvent and a higher dielectric constant than conventionally cured PI 2611.

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37

Ernyleva, S. E., V. O. Litvin, O. T. Loza, and I. L. Bogdankevich. "Promising source of high-power broadband microwave pulses with radiation frequency variable up to two octaves." Technical Physics 59, no. 8 (August 2014): 1228–32. http://dx.doi.org/10.1134/s1063784214080106.

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38

Cauchois, Romain, Mohamed Saadaoui, Abdelwahhab Yakoub, Karim Inal, Beatrice Dubois-Bonvalot, and Jean-Christophe Fidalgo. "Impact of variable frequency microwave and rapid thermal sintering on microstructure of inkjet-printed silver nanoparticles." Journal of Materials Science 47, no. 20 (March 9, 2012): 7110–16. http://dx.doi.org/10.1007/s10853-012-6366-6.

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39

Susek, Waldemar, and Bronisław Stec. "Broadband Microwave Correlator of Noise Signals." Metrology and Measurement Systems 17, no. 2 (January 1, 2010): 289–98. http://dx.doi.org/10.2478/v10178-010-0025-5.

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Broadband Microwave Correlator of Noise SignalsA real narrowband noise signal representation in the form of an analytical signal in the Hilbert space is presented in the paper. This analytical signal is illustrated in a variable complex plane as a mark with defined amplitude, phase, pulsation and instantaneous frequency. A block diagram of a broadband product detector in a quadrature system is presented. Measurement results of an autocorrelation function of a noise signal are shown and the application of such solution in a noise radar for precise determination of distance changes as well as velocities of these changes are also presented. Conclusions and future plans for applications of the presented detection technique in broadband noise radars bring the paper to an end.

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40

AHMED, RIZWAN, and TASNIM AZIM. "AMPLITUDE CONTROL OF SPONTANEOUS EMISSION." International Journal of Modern Physics B 23, no. 26 (October 20, 2009): 5143–54. http://dx.doi.org/10.1142/s021797920905328x.

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We study the control of spontaneous emission in four-level atomic system driven by two fields. We show that with the variation of dynamical variable, namely, Rabi frequency, a wide variety of spectral behavior can be obtained, including extreme spectral narrowing. In our system, the spectrum of the spontaneous emission is independent of the phase associated with microwave field.

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41

Casas, Francisco J., David Ortiz, Beatriz Aja, Luisa de la Fuente, Eduardo Artal, Rubén Ruiz, and Jesús M. Mirapeix. "A Microwave Polarimeter Demonstrator for Astronomy with Near-Infra-Red Up-Conversion for Optical Correlation and Detection." Sensors 19, no. 8 (April 19, 2019): 1870. http://dx.doi.org/10.3390/s19081870.

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This paper presents a 10 to 20 GHz bandwidth microwave polarimeter demonstrator, based on the implementation of a near-infra-red frequency up-conversion stage that allows both the optical correlation, when operating as a synthesized-image interferometer, and signal detection, when operating as a direct-image instrument. The proposed idea is oriented towards the implementation of ultra-sensitive instruments presenting several dozens or even thousands of microwave receivers operating in the lowest bands of the cosmic microwave background. In this work, an electro-optical back-end module replaces the usual microwave detection stage with Mach–Zehnder modulators for the frequency up-conversion, and an optical stage for the signals correlation and detection at near-infra-red wavelengths (1550 nm). As interferometer, the instrument is able to correlate the signals of large-format instruments, while operating as a direct imaging instrument also presents advantages in terms of the possibility of implementing the optical back end by means of photonic integrated circuits to achieve reductions in cost, weight, size, and power consumption. A linearly polarized input wave, with a variable polar angle, is used as a signal source for laboratory tests. The receiver demonstrator has proved its capabilities of being used as a new microwave-photonic polarimeter for the study of the lowest bands of cosmic microwave background.

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42

Dargar, Shashi K., and Viranjay M. Srivastava. "Moisture content investigation in the soil samples using microwave dielectric constant measurement method." International Journal of Electrical and Computer Engineering (IJECE) 10, no. 1 (February 1, 2020): 704. http://dx.doi.org/10.11591/ijece.v10i1.pp704-710.

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The microwaves of typical frequency ranges of 3 GHz to 30 GHz have been in use for remote sensing applications which are progressing rapidly. The microwaves can sense existing moisture in any material that absorbs moisture such as soil or vegetation. In case of soils which may be comprised of variable mix proportionate of solids, liquids or gases and distinct textures subjected to the associated size and the arrangements of soil particles. Hence, the moisture absorption by a specific type of soil used to be different. The inherent physical and electrical properties such as color, texture, grains, dielectric constant, conductivity or permeability, etc. differentiate various soils. In this work, authors present soil moisture measurement by simple estimation of emissivity i.e. the ratio of energy radiated by an object to absorbing the body of same physical temperature. A strategic method of measuring dielectric constant using a microwave signal is used in this research work. The measurement of the dielectric constant of the soils collected from the specific regions and analysis of results has been reported. The proposed method is less complex and can further be used for the identification of soil moisture and agricultural applications.

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43

Tang, Yongfu, Lin Meng, Hailong Li, Ling Zheng, Bin Wang, and Feina Zhang. "Design of a high-efficiency dual-band coaxial relativistic backward wave oscillator with variable coupling impedance and phase velocity." Laser and Particle Beams 31, no. 1 (November 28, 2012): 55–62. http://dx.doi.org/10.1017/s0263034612000882.

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AbstractA dual-band high-efficiency coaxial relativistic backward wave oscillator (CRBWO) with asymmetric resonant reflector is designed and presented in this paper. Improved sectioned coaxial slow wave structure (SWS) with stepwise variation of coupling impedance and phase velocity is employed, and the performance of the dual-band CRBWO is investigated by use of a 2.5-D particle-in-cell (PIC) simulation code. When the diode voltage is 510 kV and beam current is 9.03 kA, an average microwave power of 1.0 GW with power conversion efficiency of 21.7% is obtained. Synchronously radiating dual-band frequencies of 8.1 GHz and 9.9 GHz are obtained, corresponding to C-band and X-band, respectively. A more clear and stable beating radiation microwave power with beating frequency of 1.8 GHz is acquired.

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44

Diop, Mamadou Diobet, Marie-Claude Paquet, David Danovitch, and Dominique Drouin. "Void-Free Underfill Process With Variable Frequency Microwave for Higher Throughput in Large Flip Chip Package Application." IEEE Transactions on Device and Materials Reliability 15, no. 2 (June 2015): 250–57. http://dx.doi.org/10.1109/tdmr.2015.2408211.

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45

Liao, Yumei, and Wei Wei. "The Regularity of Solution for Weakly Coupled System Derived by Microwave Heating Model." Mathematics 7, no. 6 (June 2, 2019): 501. http://dx.doi.org/10.3390/math7060501.

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In this paper, we study the regularity of the weak solution of the coupled system derived from the microwave heating model with frequency variable. We first show that the weak solution E of the system is Hölder continuous near the boundary of S = ∂ Ω . The main idea of the proof is based on the estimation of linear degenerate system in Campanato space. Then we show that the solution u of the heat conduction equation is Hölder continuous with exponent α 2 . Finally, under the appropriate conditions we show that the coupled system with microwave heating has a weak solution. Moreover the regularity of the weak solution is studied.

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46

Colombini, Elena, Katia Papalia, Stefano Barozzi, Francesco Perugi, and Paolo Veronesi. "A Novel Microwave and Induction Heating Applicator for Metal Making: Design and Testing." Metals 10, no. 5 (May 21, 2020): 676. http://dx.doi.org/10.3390/met10050676.

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The use of microwave heating in primary metallurgy is gaining an increasing interest due to the possibility to selectively process ores and to volumetrically heat large amounts of low-thermal conductivity minerals. In this paper the study, development and testing of a new applicator combining the use of microwave and induction heating for rapid reduction of metal containing oxides is described. Numerical simulation was used in order to achieve the proper control over heat generation, considering the use of microwave solid state generators. A prototype, with a capacity up to 5 liters of standard input feed but with the predisposition for continuous processing has been designed, built and tested on reference loads like iron oxide powders and pellets. Results on the microwave heating part of the applicator indicate that it allows to efficiently and rapidly process these kinds of loads, which change from dielectric to conductors as reduction proceeds. The use of variable frequency solid state microwave generators allows to maximize energy efficiency and to controllably change the heating pattern inside the load.

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Evseev, Vladimir, Mikhail Ivlev, Elena Lupanova, Sergey Nikulin, Vitaliy Petrov, and Andrey Terentyev. "Automation of S-parameters measurements of high-power microwave transistors in a contact device with tunable strip matching circuits." ITM Web of Conferences 30 (2019): 11002. http://dx.doi.org/10.1051/itmconf/20193011002.

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In the practice by microwave power transistor amplifiers developing, the variable load method is usually used to determine the impedances of matching circuits in the complex conjugate matching mode. This solution involves the use of expensive equipment - coaxial impedance tuners and contact devices for mounting transistors in low impedance strip lines. An even more complicated and expensive way is the concept of X- parameters, based on the use of unique measuring equipment - a non-linear vector network analyzer, and a simulator for non-linear circuits design. The article proposes an alternative solution adapted to the operation of the transistor in real conditions and allowing to design the output stages of microwave power amplifiers using analysis and optimization of linear electrical circuits. The essence of the proposed solution is to automate the measurement of non-linear S-parameters of high-power microwave transistors in a contact device with tunable strip matching circuits for various DC supply voltage, frequency and input power mode in case of continuous or pulse input signal. The nonlinear S-parameters of the contact device are measured using the method of spatially remote variable load in the frequency range, in which the line conditioning and the maximum output power are achieved. The minimum of the reflected wave amplitude and the maximum gain are reached using movable strip matching transformers. The S-parameters measured in the coaxial line are automatically recalculated to the physical boundaries of the transistor by registering the positions of the input and output strip transformers.

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Fencl, Martin, Michal Dohnal, Pavel Valtr, Martin Grabner, and Vojtěch Bareš. "Atmospheric observations with E-band microwave links – challenges and opportunities." Atmospheric Measurement Techniques 13, no. 12 (December 4, 2020): 6559–78. http://dx.doi.org/10.5194/amt-13-6559-2020.

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Abstract. Opportunistic sensing of rainfall and water vapor using commercial microwave links operated within cellular networks was conceived more than a decade ago. It has since been further investigated in numerous studies, predominantly concentrating on the frequency region of 15–40 GHz. This article provides the first evaluation of rainfall and water vapor sensing with microwave links operating at E-band frequencies (specifically 71–76 and 81–86 GHz). These microwave links are increasingly being updated (and are frequently replacing) older communication infrastructure. Attenuation–rainfall relations are investigated theoretically on drop size distribution data. Furthermore, quantitative rainfall estimates from six microwave links, operated within cellular backhaul, are compared with observed rainfall intensities. Finally, the capability to detect water vapor is demonstrated on the longest microwave link measuring 4.86 km in path length. The results show that E-band microwave links are markedly more sensitive to rainfall than devices operating in the 15–40 GHz range and can observe even light rainfalls, a feat practically impossible to achieve previously. The E-band links are, however, substantially more affected by errors related to variable drop size distribution. Water vapor retrieval might be possible from long E-band microwave links; nevertheless, the efficient separation of gaseous attenuation from other signal losses will be challenging in practice.

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Garbuglia, Federico, Domenico Spina, Dirk Deschrijver, and Tom Dhaene. "Evaluation of Generative Modeling Techniques for Frequency Responses." Engineering Proceedings 3, no. 1 (October 30, 2020): 7. http://dx.doi.org/10.3390/iec2020-06970.

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During microwave design, it is of practical interest to obtain insight in the statistical variability of a device’s frequency response with respect to several sources of variation. Unfortunately, the frequency response acquisition can be particularly time-consuming or expensive. This makes uncertainty quantification unfeasible when dealing with complex networks. Generative modeling techniques that are based on machine learning can reduce the computation load by learning the underlying stochastic process from few instances of the device response and generating new ones by executing an inexpensive sampling strategy. This way, an arbitrary number of frequency responses can be obtained that are drawn from a probability distribution that resembles the original one. The use of Gaussian Process Latent Variable Models (GP-LVM) and Variational Autoencoders (VAE) as modeling algorithms will be evaluated in a generative framework. The framework includes a Vector Fitting (VF) pre-processing step which guarantees stability and reciprocity of S-matrices by converting them into a suitable rational model. Both GP-LVM and VAE are tested on the S-parameter responses of two linear multi-port network examples.

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Qi, Ben Sheng, and Jun Juan Shi. "A Compact UWB Monopole Micro-Strip Antenna with a Desirable Band Notch." Applied Mechanics and Materials 687-691 (November 2014): 4136–39. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4136.

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In this paper, a low-cost compact monopole UWB antenna with variable band notch characteristics is presented. The antenna is complemented on FR4 substrate with the whole size of . And the proposed antenna consists of a radiating patch with two symmetric semiellipse parasitic patches. A U-shaped slot is added to achieve a desired band notch frequency. It is excited by a 50 microstrip-line feed. A partial trapezoid ground plane with two symmetric L-shaped slots and two parasitic patches both can help to obtain higher frequency bandwidth more than 139% (2.8 GHz~15.6 GHz). The substrate with two circular holes can slightly improve the lower frequency characteristic. The simulation of the proposed antenna is achieved by CST Microwave Studio Software.

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